<template>
  <div class="goods-image">
    <div v-if="isShow" class="large" :style="[{backgroundImage:`url(${images[currIndex]})`},bgPosition]"></div>
    <div class="middle" ref='target'>
      <!-- 左侧的大图 -->
      <img :src="images[currIndex]" alt="">
      <!-- 遮罩层 -->
      <div v-if='isShow' class="layer" :style='position'></div>
    </div>
    <!-- 右侧的缩略图 -->
    <ul class="small">
      <li v-for="(img,i) in images" :key="img" :class="{active:i===currIndex}">
        <img @mouseenter="currIndex=i" :src="img" alt="">
      </li>
    </ul>
  </div>
</template>
<script>
import { ref, watch, reactive } from 'vue'
import { useMouseInElement } from '@vueuse/core'
export default {
  name: 'GoodsImage',
  props: {
    images: {
      type: Array,
      default: () => []
    }
  },
  setup (props) {
    const currIndex = ref(0)
    const isShow = ref(false)
    // 监听的区域DOM
    const target = ref(null)
    // 记录遮罩层的坐标
    const position = reactive({
      left: 0,
      top: 0
    })
    // 图片背景的坐标
    const bgPosition = reactive({
      backgroundPositionX: 0,
      backgroundPositionY: 0
    })
    const { elementX, elementY, isOutside } = useMouseInElement(target)
    watch([elementX, elementY, isOutside], () => {
      // 控制遮罩层和预览图显示
      isShow.value = !isOutside.value
      // 鼠标在区域外面移动不进行计算
      if (isOutside.value) return
      // 水平方向
      if (elementX.value < 100) {
        // 左边界
        position.left = 0
      } else if (elementX.value > 300) {
        // 右边界
        position.left = 200
      } else {
        // 中间状态
        position.left = elementX.value - 100
      }

      // 垂直方向
      if (elementY.value < 100) {
        // 上边界
        position.top = 0
      } else if (elementY.value > 300) {
        // 下边界
        position.top = 200
      } else {
        // 中间状态
        position.top = elementY.value - 100
      }

      // 小的遮罩层移动100，大的背景图反方向移动200
      bgPosition.backgroundPositionX = -position.left * 2 + 'px'
      bgPosition.backgroundPositionY = -position.top * 2 + 'px'

      // 控制左侧遮罩层位置
      position.left += 'px'
      position.top += 'px'
    })

    return { currIndex, isShow, target, position, bgPosition }
  }
}
</script>
<style scoped lang="less">
.goods-image {
  width: 480px;
  height: 400px;
  position: relative;
  display: flex;
  .middle {
    width: 400px;
    height: 400px;
    background: #f5f5f5;
    position: relative;
    cursor: move;
    .layer {
      width: 200px;
      height: 200px;
      background: rgba(0, 0, 0, 0.2);
      left: 0;
      top: 0;
      position: absolute;
    }
  }
  z-index: 500;
  .large {
    position: absolute;
    top: 0;
    left: 412px;
    width: 400px;
    height: 400px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    background-repeat: no-repeat;
    background-size: 800px 800px;
    background-color: #f8f8f8;
  }
  .small {
    width: 80px;
    li {
      width: 68px;
      height: 68px;
      margin-left: 12px;
      margin-bottom: 15px;
      cursor: pointer;
      &:hover,
      &.active {
        border: 2px solid @xtxColor;
      }
    }
  }
}
</style>
